样品粒度对近红外分析结果的影响

探讨了样品粉碎粒度对近红外光谱测定结果的影响。在近红外分析仪的定标和测定中,要特别注意对粉碎机和筛网的选择,筛孔直径不能大于1.0mm,同时定标样品和测试样品的粉碎条件应当完全一致,才能减少误差     

人参成份的近红外光谱定量分析

人参是我国东北三宝之首,具有较高的药用价值。目前对其主要成份人参总糖、皂苷等成份检测多采用繁琐的化学分析方法,耗时、成本高,同时不可避免的对样品造成损耗。采用近红外光谱分析技术对29份人参粉末样品成份进行快速、无损定量分析,获得了较高的分析精度。建立总糖、总皂苷、水分模型的预测值与化学标准值相关系数(R)分别为0.93、0.90、0.96,交叉检验标准差(RMSECV)分别为1.78、0.28、0.45。进一步深入研究有望实现珍贵的野山参样品营养成份近红外光谱无损检测。     

微型近红外光谱检测系统温度补偿的设计

针对温度影响近红外光谱的问题提出了解决方案:在MicroNIR-1700近红外光谱仪上添加了环境温度和样品温度的检测附件及应用软件,使用单总线数字温度传感器DS18B20和红外温度传感器TN901及处理电路等构成了温度补偿系统,结合MicroNIR-1700的内部命令集获得仪器的温度。这3个温度参数奠定了微型近红外光谱检测系统的温度补偿条件,可以为后续模型建立提供温度补偿信息。     

不同积分宽度平滑数据处理对近红外分析建模的影响

以在MPA型和WQF-400N傅立叶近红外光谱仪上测量的茶叶和奶粉光谱为原始光谱,利用积分法选择不同的积分区间对原始光谱进行积分,模拟不同分辨率下的光谱,建立了茶叶中咖啡碱和奶粉中脂肪的定量分析模型,研究了不同分辨率对模型精度的影响。结果显示,对茶叶和奶粉,MPA型仪器分别是分辨率为32cm^-1和16cm^-1最好,相关系数（R）、预测均方差（RMSEP）分别为0．9400、0．2900和0．8879、1．0835;WQF-400N型仪器均是分辨率为64cm^-1时最好,R,RMSEP分别为0．9258、0．3311和0．9190、0．9365。试验结果表明分辨率对模型精度有很大影响,但并不是分辨率越高越好,对具体样品和仪器存在一个最为合适的分辨率。     

近红外光谱分析的技术与应用

对近红外光谱分析数学模型的建立及应用进行了简述。     

近红外光谱在农业中的应用

介绍了近红外光谱技术的组成以及近红外光谱技术的发展历程,综述了近年来国内外近红外光谱技术在谷物、果蔬、土壤及其他方面的应用.     

PLS-近红外漫反射光谱法对氢氧化铝粉末药品非破坏定量分析

本文采用近红外漫反射光谱法对氢氧化铝粉末药品中主要成分氢氧化铝进行快速、无损定量分析。采用偏最小二乘法（PLS）建立近红外光谱信息与待测组分含量间的最佳数学校正模型。讨论了光谱的预处理方法和主成分数对PLS定量预测能力的影响,并对预测集样品含量进行预测,得到了较为满意的结果。     

中药材黄连颗粒度对近红外光谱的影响

近红外漫反射光谱易受样品颗粒度的影响。本文对10种不同粒度的黄连的近红外光谱进行分析,讨论粒度对黄连的近红外光谱强度的影响。结果发现,小粒度黄连的近红外光谱的重现性较好。当黄连粒度小于0.154 mm时,粒度变化对黄连的近红外光谱强度的影响较小。     

短波近红外光谱的盐酸环丙沙星粉末药品的定量分析

利用漫反射法获得环丙沙星短波近红外光谱(700-1100nm),采用化学计量学中的偏最小二乘法(PLS),选取不同的波长范围及不同的光谱预处理方法(一阶导数和和二阶导数)对光谱进行信息提取和分析,对盐酸环丙沙星粉末药品进行了无损非破坏定量分析,以样品中盐酸环丙沙星为活性成分建立了最佳的数学校正模型.讨论了主成分数对PLS模型定量预测能力的影响,并做了比较.     

血糖浓度的短波近红外定量分析

采用间隔偏最小二乘法(IPLS)和移动窗口偏最小二乘方法(MWPLS),在640～1 100nm范围内建立血糖短波近红外的优化模型。使用马氏距离对人血清样品中的奇异样品进行筛选,将检测光谱分别等分为2～15份进行IPLS分析,对比建立预测模型。设窗宽为151nm,成分数范围(1～20),全谱进行MWPLS,对预测模型进行优化。结果显示,依据马氏距离采用最小半球体积法能有效筛选所采集光谱中的奇异光谱,IPLS可以有效地找到葡萄糖分子官能团对应的近红外特征谱段,MWPLS能够找到适合建模的精确起止波长点,通过偏最小二乘法建立血糖浓度的预测模型,相关系数R=0.982 2,预测均方差RMSEP=0.163 5 mmol/L,偏差Bias=-0.087 3mmol/L。     

Experimental mathematical model as a generalization of sensitivity analysis of high temperature spectral emissivity measurement method

The development of an experimental mathematical model describing temperature state of the sample during high temperature spectral emissivity measurement is introduced. Dimensional analysis of the measurement process gives the physical dimensionless quantities and sensitivity analysis of the measurement process provides the large set of performed model experiments. Evaluated experimental mathematical models are presented including their accordance with model experiments. Established equations are generalization of sensitivity analysis of high temperature spectral emissivity measurement method and can be used for computation of spectral emissivity total uncertainty.     

采用相关分析解析石油产品近红外光谱

选择一系列结构上具有代表性的烃类化合物,配制不同浓度的溶液,以及它们不同浓度的重整汽油溶液,在中红外,短波近红外和长波近红外光谱仪上,分别测定溶液的中红外光谱、短波近红外光谱和长波近红外光谱。采用相关分析方法对中红外光谱和近红外光谱进行关联,确立重整汽油各结构基团吸收谱带在近红外短波区及长波区的精确位置,并考察化学环境和物理环境对谱带位置的影响。     

近红外光谱快速分析法在坤宝丸检测中的应用

目的:采用近红外光谱法对坤宝丸药粉中芍药苷含量进行快速测定。方法:以HPLC分析值作为参照,采用近红外漫反射光谱技术采集坤宝丸药粉的近红外光谱,结合偏最小二乘法建立芍药苷含量的快速测定方法,并对未知样品进行含量预测。结果:建立芍药苷校正模型R,RMSEC(%)、RMSEP(%)分别为0.96,2.708,0.44。对预测集样品预测平均相对偏差为4.2%。结论:该方法简便、快速、无损,可用于坤宝丸的快速定量分析。     

利用衰减全反射傅立叶变换红外光谱方法对乙二醇水溶液定量分析的研究

利用衰减全反射-傅立叶变换红外光谱法(ATR-FTIR)和OMNI采样器附件对乙二醇水溶液进行定量分析的研究。吸光度测量值有较宽的线性范围,重复性好。这一分析方法方便快捷、分析结果准确。     

煤炭采样机械臂的刚柔耦合动力学建模与仿真分析

基于多体动力学理论和拉格朗日方程,将煤炭采样机械臂中的大臂、小臂、伸缩臂考虑为柔性臂,结合Pro/E,ANSYS和ADAMS分别建立刚性和刚柔耦合模型,在相同驱动函数下对两种运动模型进行分析,仿真得出两种模型变化曲线,对比仿真结果表明,在研究臂架系统时,考虑各个臂杆柔性变形是非常必要的,刚柔耦合建模更符合工程实际,所得到的研究结果为采样臂动力学分析和结构优化奠定了理论基础.     

A sample construction method in kinematics characteristics domain to identify the feed drive model

The modeling accuracy of feed drive is mainly affected by two factors: the accuracy of model form and the completeness of sample data which is used to identify the parameters of the established model form. One of the main works of this study is to construct the experimental trajectories which are used to obtain the sample data. Different from the trajectories selected based on the researcher's experience in previous literatures which lacks theoretical evidence to confirm the completeness of the sample data, in this paper, a reverse construction method of experimental trajectory is proposed based on the required sample data. First, the completeness of sample data is analyzed, and the samples are generated by using the Hammersley sequence method. Then, the experimental trajectories are derived. In addition, considering that the data of the feed system has temporal correlations between the adjacent motion states in time sequence, this study made some improvements on the modeling framework composed of the first-principle model and machine learning model. The experiments conducted in the actual feed drive system showed that the maximum prediction error of the tracking error is 7.8%, which confirmed the effectiveness of the designed trajectories and the high accuracy of the proposed model. Furthermore, the advantage of the proposed trajectory is confirmed by the comparison experiment. At the same time, the same trajectories are used to train different model forms to verify the advantage of the proposed model. The proposed feed drive modeling method can be used for designing a high-performance feed drive control system or compensating errors when generating motion commands, thereby improving the machining accuracy of machine tool.     

棒材热连轧温度场数学模型探究

针对棒材生产中断面变化的几何特点,以Fourie热传导微分方程式为基础,用差商代替微分得到了棒材热传导微分方程的差分形式方程的数学模型,该模型可以为棒材温度计算提供理论指导。     

Study of sample temperature compensation in the measurement of soil moisture content

Since the near-infrared (NIR) spectrum is susceptible to sample temperature fluctuations, we investigate the influence of sample temperature on the predictive power of calibration model for soil moisture content (MC) and propose the multi-source information fusion technology based on back propagation neural network (BPNN) to compensate for sample temperature effect. With the discrete wavelet transform (DWT) as the pre-processing method and the least squares support vector machine (LS-SVM) regression as the modeling method, a model at 20 °C to predict MC of the soil samples at other temperatures was established. The results show that except for 20 °C, the root mean square error of prediction (RMSEP) are large. We analyze the predicted results with the dual-factor analysis of variance without duplication and the result shows that the effect of sample temperature on the prediction model for soil MC is significant. A temperature compensation model was then established with combining of soil MC and sample temperature based on BPNN. The predicted results showed that the prediction precision of the model was improved significantly.     

模态分析方法综述

综述模态分析在研究结构动力特性中的应用,介绍模态分析的两大方法:数值模态分析与试验模态分析。并着重介绍目前的研究热点———工作模态分析,对其方法存在的问题进行评述。     

可转位浅孔钻非稳态加工的数学模型

以刀体上装有两个等边不等角六边形硬质合金可转位刀片的浅孔钻为例,用向量矩阵法分析了可转位浅孔钻的几何参数.根据浅孔钻的加工特征将其分成稳态和非稳态两个工作状态,将非稳态加工分为钻入五个阶段和钻出三个阶段,并分别对其相应的几何参数的计算建立了数学模型.为对浅孔钻进行进一步力学建模、对其所受切削力、切削热的研究,对浅孔钻结构的改进、使用等打下了必要的基础.